This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Metal nanoparticles (NP) have gained interest as a novel platform for integrated cancer imaging and therapy due to their highly desirable spectral and molecular properties. While the targeting of macromolecular anti-cancer drugs has been studied in great detail, there is currently little known about the dynamics of metal nanoparticle targeting primarily due to the lack of techniques to monitor them in vivo. The proposed project will develop Modulated Imaging (MI) as a three dimensional quantitative imaging tool to monitor NP's in bulk tissue (Aim 1). We will validate this system in tissue simulating phantoms and in murine tumor xenografts in vivo. This system will be used to study the kinetics of NP tumor targeting (Aim 2). In particular, we will study the effect of nanoparticle size, shape, and targeting strategy (i.e. passive vs. ligand-mediated) on the accumulation rate and affinity in murine tumors.